The following refers to a Dell C640 (2003) laptop running Windows XP
Professional.

One month ago, Excel was functioning without problems. Today, when I tried
to open Excel, the following notification appeared:  "Windows is configuring
Microsoft Office XP Professional with Front Page..."   I exited and restarted
but Excel still did not work.

One week ago, a Windows automatic updates notification appeared stating that
Office XP Service Pack 3 was available.  When I clicked on Install, I
received the following notification: " ...place a Microsoft Office XP
Professional with Front Page CD in the CD drive..."  I canceled the
installation since the software CDs were lost years ago in a move.  

Did attempting to install Office XP Service Pack 3 change something in the
Excel program that makes it not function now?   The rest of the programs that
are part of Office XP are working  fine.  What can I do to make Excel work
again?

Any suggestions are welcome, just please be aware that I have very little
knowledge or experience with the operating system.  

Thank you.